The present invention is related to multi-level converters, and in particular to controllers for multi-level converters.
Multi-level converters, such as three-level converters, are oftentimes used to convert an alternating current (AC) voltage into a direct current (DC) voltage, or to convert a direct current (DC) voltage into an alternating current (AC) voltage. A three-level converter is different from a typical converter because switches of the three-level converter are provided in separate levels to provide an electrical connection between an AC terminal and either a positive DC terminal, a negative DC terminal, or a midpoint or neutral-clamped terminal.
Ideally, the switches are controlled to provide the desired voltages at each of the AC terminals of the converter, and there will be no common mode voltage at the AC terminals of the converter. There is no common mode voltage at the AC terminals of the converter only if the sum of all AC terminal voltages to ground is zero. Previously, controllers used to control the state of the plurality of switches associated with the three-level converter have utilized space vector modulation to prevent the generation of common mode voltage at the AC terminals of the three-level converter.